The heavy rain across the area over the last month is washing bacteria through our waterways.

The PBC Health Department said the recent rains are to blame for the issues that arise at area beaches.

At Dubois Park in Jupiter - "Usually it flushes itself very well with tidal flushing coming off the inlet. It's got a good flow. But when we have these heavy rains, because it's a little more inland and closed in, it has a tendency to capture a lot of the bacteria," said Tim O'Connor, a spokesman for the Florida Department of Health for Palm Beach County.

Currently, the department says all the beaches are safe, from Boca Raton to Jupiter. Boca Raton beaches had received poor results from water testing and were closed for a couple of days last week, but the beaches are now open.

Mr. O'Connor said analysts must collect samples from at least 18 inches of water and at least three feet into the waterway.

"And then they turn that into the lab for testing for enterococci -- which is a bacteria that primarily comes from the intestines of warm blooded animals," he said.

But they only test every other Monday, partly due to efficiency.

"We used to do it weekly, but the data showed us that it's just as effective to do twice a month," he said. "95 percent of the time, our beaches test in the good range."

He added testing on Monday, following usually busy weekends, is a good indicator of bacteria levels. It takes the health department 24 hours to get water sample results. If the levels are high, the beach is closed -- but lifeguards continue testing the water every day until the water comes back to normal. Beach closures usually last about two days.

There are also other factors like watercraft and sewage spills that can contribute to unexpected bacteria levels at area beaches. Those instances are rare.

"A ship for example, has emptied its bilge...and then that gets carried in and we'll run into it that way," said Mr. O'Connor.

The changing tides can also affect the color of the water. On Tuesday, Dubois Park's water looked dark brown, a stark contrast to the deeper blue color.

"When it's going to low tide, it pulls along this trough here and goes back out to the ocean. And that's why we have a little bit of brown tint because it's coming from deeper in the Intracoastal and back in a lake here," said Hannah Forrest, a lifeguard at Dubois Park for Palm Beach County. "It's coming from deeper Intracoastal where the water is brackish water."